JPH05158565A - Reactive power compensating method - Google Patents

Abstract

PURPOSE:To compensate reactive power by always operating efficiently an inverter device. CONSTITUTION:A reactive power fluctuation portion Q of a fluctuation load 12 is detected by a detecting part 16. When this detection value is within a first set range, an output for controlling an inverter device 13 is provided from a control circuit 17. Subsequently, when the detection value goes over a first set range and enters a second set range, a first phase advance capacitor 14a is connected to a system 11, and when the detection value goes over a second set range, a second phase advance capacitor 14b is also connected to the system 11, and by both the capacitors 14a, 14b and an inverter device 13, a compensation of reactive power is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactive power compensation method in which an inverter device and a plurality of phase advancing capacitors are combined.

[0002]

2. Description of the Related Art FIG. 4 is a single line connection diagram showing a reactive power compensation method in which an inverter device and a phase advancing capacitor are combined.
Reference numeral 11 is a system to which a variable load 12 is connected via a transformer (not shown). 13 is an inverter device,
A phase advancing capacitor 14 compensates the reactive power of the fluctuating load 12 by the inverter device 13 and the phase advancing capacitor 14. 15 is the reactor, 16 is the reactive power fluctuation ((△
Q) A detector, 17 is a control circuit, and 18 is a gate circuit.

In the reactive power compensating method shown in FIG. 4, when the progressive reactive power is compensated from the reactive power "0",
The phase advancing capacitor 14 and the inverter device 13 are made to operate with the same capacity, and the inverter device is continuously variably controlled to 1/2 of the rated capacity of the entire compensator.

[0004]

If the inverter device is continuously variably controlled up to 1/2 of the rated capacity as described above, there is a problem that the inverter device cannot operate efficiently in the entire capacity range of the inverter device. .. Since the conversion efficiency of the inverter device is represented by {output capacity / (output capacity + loss of inverter device)} × 100%, the loss of the inverter device varies much over the range of output capacity (0% to 100%). Without it, it becomes almost constant,
This is because the efficiency is most efficient in the vicinity of the rated capacity from the above formula.

The present invention has been made in view of the above circumstances, and when the inverter device and the phase-advancing capacitor are combined to compensate the reactive power, the reactive power compensation is made to always operate the inverter device efficiently. The purpose is to provide a method.

[0006]

In order to achieve the above object, the present invention provides a method for compensating the reactive power of a fluctuating load with a plurality of phase advancing capacitors and an inverter device as shown in FIG. After detecting the reactive power fluctuation of the fluctuating load in step S ₁ , it is determined in step S ₂ whether the value of the fluctuation is within the first setting range of the compensation capacity,
The determination result is driving a inverter device compensates the reactive power at step S _3, if that range, beyond the first set range at step S _4, step S if the second set range
_{In step 5} , the first phase advancing capacitor is turned on, and the inverter device is operated to compensate the reactive power together with the first phase advancing capacitor. If the second setting range is exceeded in step S ₄ , the step S ₆ is performed. 1. Put the second phase advance capacitor,
In addition, the inverter device is operated to compensate the reactive power together with the first and second phase advance capacitors.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The same parts as those in FIG. 4 are designated by the same reference numerals. In the embodiment shown in FIG. 2, a plurality of phase advancing capacitors (two in FIG. 2 are shown) are provided, and the first and second phase advancing capacitors 14a, 14b are provided with first and second reactors 15a, 15a. 1
After connecting 5b in series, switches 19a and 19b are connected.
It is connected to the system 11 via. In addition, 20 is a current transformer, 21 is a transformer, and this current transformer 20 and the transformer 21
Is provided to the reactive power fluctuation component (ΔQ) detection unit 16.

Next, the operation of the above embodiment will be described. The variation ΔQ of the fluctuating load 12 is detected by the detecting unit 16. The value detected by the detector 16 is input to the control circuit 17. In this control circuit 17, a control output is given to the gate circuit 18 for performing gate control of the inverter device 13 while the value is in the first setting range (for example, 0% to 50%) of the compensation capacitance. In accordance with this control output, the gate circuit 18 controls the output capacity of the inverter device 13 as indicated by the straight line A in FIG. 3 to compensate the reactive power of the grid 11. At this time, since the first and second phase advance capacitors 14a and 14b are not turned on, the number of the put-in capacitors is "0" as shown in FIG.

Next, if the detected value in the detector 16 exceeds the first set range (for example, 50%) and is within the second set range (for example, 75%), the control circuit 17 outputs an output for turning on the switch 19a. It When the switch 19a is turned on, the first
The phase-advancing capacitor 14a is put into the system 11, and the reactive power is compensated by the capacitor 14a and the inverter device 13. In this case, the inverter device 13 is variable in the range of 50% to 100%, for example. A straight line B in FIG. 3 is a capacitance change of the inverter device 13 when one phase-advancing capacitor is turned on.

The detected value is within the second set range (for example, 75
%) Is exceeded, the control circuit 17 causes the switch 19
An output for turning on both a and 19b is transmitted. As a result, the first and second phase advancing capacitors 14a and 14b are turned on to the grid 11 and the inverter device 13 is controlled, whereby reactive power is compensated. In this case, the inverter device 13 has 50% of the same capacity as above.
It is 100% variable. The straight line C in FIG. 3 represents the capacity change of the inverter device 13 when two phase-advancing capacitors are inserted. In the above embodiment, the phase advancing capacitor is 2
Although the case of a unit has been described, three or more units may be used.

[0011]

As described above, according to the present invention,
By performing the reactive power compensation by combining the inverter device and the phase advancing capacitor, the reactive power can be compensated while always operating the inverter device efficiently.

[Brief description of drawings]

FIG. 1 is a flowchart showing a driving method according to the present invention.

FIG. 2 is a single wire connection diagram showing an embodiment of the present invention.

FIG. 3 is a control characteristic diagram showing an example of a phase advancing capacitor ¼ capacitance.

FIG. 4 is a single line connection diagram showing a conventional example.

[Explanation of symbols]

11 ... system, 12 ... fluctuating load, 13 ... inverter device,
14a, 14b ... First and second phase advance capacitors, 15
a, 15b ... First and second reactors, 16 ... Reactive power fluctuation detection unit, 17 ... Control circuit, 18 ... Gate circuit, 19
a, 19b ... Switch.

Claims (1)

[Claims] 1. A method of compensating reactive power of a fluctuating load by a plurality of phase advancing capacitors and an inverter device,
After detecting the reactive power fluctuation of the fluctuating load, it is judged whether the value of the fluctuation is within the first setting range of the compensation capacity. If the judgment result is in that range, the inverter device is operated to compensate the reactive power. However, if it exceeds the first setting range and is within the second setting range, the first phase advance capacitor is turned on, and the inverter device is operated to compensate the reactive power together with the first phase advance capacitor. If the setting range is exceeded, the first and second
A reactive power compensating method characterized in that a phase advancing capacitor is turned on, and an inverter device is operated to compensate reactive power together with the first and second phase advancing capacitors.